From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yx0-f189.google.com (mail-yx0-f189.google.com [209.85.210.189]) by ozlabs.org (Postfix) with ESMTP id 259AEB7CEF for ; Sat, 27 Mar 2010 10:53:54 +1100 (EST) Received: by yxe27 with SMTP id 27so5068596yxe.17 for ; Fri, 26 Mar 2010 16:53:52 -0700 (PDT) MIME-Version: 1.0 Sender: glikely@secretlab.ca In-Reply-To: <201003172118.41559.temerkhanov@cifronik.ru> References: <201003172118.41559.temerkhanov@cifronik.ru> From: Grant Likely Date: Fri, 26 Mar 2010 17:53:32 -0600 Message-ID: Subject: Re: [PATCH] [RFC] Xilinx MPMC SDMA subsystem To: Sergey Temerkhanov , "Steven J. Magnani" , microblaze-uclinux@itee.uq.edu.au, Linux Kernel Mailing List Content-Type: text/plain; charset=KOI8-R Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , I've not got time to review this patch right now, but Sergey and Steven, you both posted MPMC drivers on the same day; Steven on the microblaze list and Sergey on the powerpc list. Can you two please coordinate and figure out how to mork toward a single driver that will meet both your needs? I don't want to have 2 drivers (3 if you count the ll_temac driver) in mainline for the same hardware interface. Thanks, g. On Wed, Mar 17, 2010 at 12:18 PM, Sergey Temerkhanov wrote: > This patch adds generic support for Xilinx MPMC SoftDMA channels which ar= e > used by, e.g., LLTEMAC and other IP cores (including custom cores). So, t= he > implemented functions include only SDMA channels enumeration and control > (finding device by phandle property, channel reset, initialization of RX/= TX > links, enabling/disabling IRQs, =9AIRQ coalescing control and submission = of > descriptors (struct sdma_desc). > > The users of this subsystem are supposed to get the pointer to the struct > sdma_device by phandle (using sdma_find_device() function), fill the stru= ct > sdma_client with pointers to the callback functions which are called on r= x/tx > completion, on error, and when sdma_reset is called by any client and the= n > register the client with add_client() (sdma_del_client can be used to > unregister the struct sdma_client) > > Also, some auxiliary functions are provided to check the status of descri= ptors > (busy, done, start of packet, end of packet). > > The user is also responsible for maintenance of linked descriptors queue, > proper initialization of their fields, and submission of the descriptors = list > to SDMA channel. IRQ acknowledge must be performed by user too (calling > sdma_[rx|tx]_irq_ack respectively in [rx|tx]_complete callbacks). Also on= RX > side user must check the __be32 user[4] fields of descriptors to get the > information supplied by SDMA channel. > > This code uses SDMA channels in "Tail pointer fashion", i.e. the call to > sdma_[rx|tx]_init is performed only once after reset and then only sdma_[= rx| > tx]_submit calls are used to update the pointer to the last descriptor in= SDMA > channel. > > Simple bus driver for MPMC is also added by this patch. > > This code is in production use with our internal LLTEMAC driver implement= ation > since 2008 and with a few custom cores drivers since 2009. > > This code currently supports only soft MPMCs, i.e., only SDMA channels wi= th > memory-mapped registers. In order to support channels with DCR, a few > modifications are needed. > > Any comments and suggestions are appreciated. > > Regards, Sergey Temerkhanov, Cifronic ZAO > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.